Advanced Functional Materials· 2026Q1
Atomic‐Scale Cation Partitioning Links Reaction‐Product Chemistry to Molten‐Silicate Passivation in Rare‐Earth Tantalates
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- 2026year
Short summary
Rare-earth tantalates (RETa3O9) form protective passivation layers against molten silicate (CMAS) attack by controlling cation partitioning into specific reaction product phases, with EuTa3O9 forming a durable bilayer barrier.
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Key points
- Rare-earth tantalates (RETa3O9) form protective reaction layers against molten silicate (CMAS) corrosion.
- The structure of these layers, specifically cation partitioning into AX2O6 and B2Y2O7 phases, dictates passivation effectiveness.
- Rare-earth ionic size governs access to different reaction pathways (AX2O6-, B2Y2O7-, and CaZrO3-containing).
- Eu-centered high-entropy RETa3O9 compositions demonstrate resistance to bulk penetration and reduced thermal conductivity (8.3% lower than EuTa3O9 at 1200°C).
AI-generated from the title and abstract; the full text is not read.
Abstract
ABSTRACT Molten silicates can be immobilized by protective reaction products or continue to penetrate oxide ceramics, but the structural features that distinguish these pathways remain unclear. Here we examine CMAS reactions with RETa 3 O 9 and connect crystallographic cation partitioning in corrosion products with passivation across rare‐earth chemistry, melt composition, and multicomponent design. EuTa 3 O 9 forms a durable bilayer comprising a dense AX 2 O 6 barrier and a cation‐sequestering B 2 Y 2 O 7 layer; a related consumption–barrier architecture persists in Fe‐rich lunar‐ and Martian‐regolith analogue melts. Across 11 RETa 3 O 9 compositions, rare‐earth size acts as a structural descriptor for access to AX 2 O 6 ‐, B2Y2O 7 ‐, and CZO 4 ‐containing reaction pathways. Using this relationship as a design constraint, Eu‐centred high‐entropy RETa 3 O 9 compositions retain resistance to bulk penetration while reducing thermal conductivity. HEC‐2 forms an 84.4 µm reaction layer after 100 h at 1300°C and exhibits an 8.3% lower calculated effective thermal conductivity than EuTa 3 O 9 at 1200°C. These results link reaction‐product chemistry to mechanism‐constrained composition design for high‐temperature protective ceramics.
The authors' abstract, as published at the source. Advanced Functional Materials, 2026 · DOI ↗
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Field: Ceramics and Composites
Ceramics and CompositesMaterials Science